Antiknock compositions



United States Patent 3,272,606 ANTIKNOCK COMPOSITIONS Jerome E. Brown, Detroit, Mich, and Hymiri Shapiro and Earl G. De Witt, Baton Rouge, La., assignors to Ethyl Corporation, New York, N.Y., a corporation of Virginia No Drawing. Filed Aug. 18, 1958, Ser. No. 755,401 3 Claims. (Cl. 44-69) This application is in part a continuation of our copending application Serial No. 696,961, filed November 18, 1957, which in turn is a continuation-in-part of our prior application Serial No. 325,224, filed December 10, 1952, now Patent 2,818,416.

This invention relates to a fundamental advance in the antiknock art. More particularly, this invention relates to gasoline having markedly improved performance characteristics, notably very high octane quality, as a result of the presence therein of novel antiknock fluid compositions.

It has long been known that lead alkyls have the highly important property of raising the octane quality of gasoline. For over thirty years tetraethyllead has been used as the commercial antiknock agent. Over the years, improvements in refinery technology have also contributed in large measure to continuous increases in gasoline quality. In fact, the conjoint use of tetraethyllead with progressively higher octane base stocks resulting from these refinery improvements has raised the average research octane number of all premium motor fuels marketed in the United States from 86 in 1946 to 96 in 1956. By the same token, the average research octane number of all non premium motor fuel sold in the United States went from 80 to 89 in this same period. The provision of these higher octane gasolines has, in turn, enabled the progressive development of more efficient engines. For example, the average compression ratio of passenger car engines made in this country was 50 percent higher in 1946 than it was in 1925, whereas by 1956 it was 93 percent higher than in 1925. This upward trend in engine compression ratios continues. However, a new problem has arisen in attempting to provide still higher octane quality fuels to satisfy the forthcoming higher compression engines.

To gain additional octane numbers by relying on refining methods alone has been too expensive to be feasible since these octane numbers are being superimposed upon fuels which already are at very high octane levels. In other words, it costs much more to refine into a fuel an incremental gain of an octane number starting with a 96 octane fuel than it does with an 86 octane fuel. Thus, the use of higher concentrates of tetraethyllead has become an economic necessity. Accordingly, the average tetraethyllead content of premium motor fuels sold in the United States has gone up from 1.5 cc. per gallon in 1946 to 2.5 cc. per gallon in 1954. In the same time period, the average tetraethyllead content of nonpremium motor fuels sold in the United States has risen from 1.1 to 2.2 cc. per gallon. It is evident, therefore, that the petroleum industry is rapidly approaching the maximum permissible tetraethyllead concentration-3 cc. per gallon of motor fuel. Thus, facing the petroleum refiner is the extremely difiicult problem of supplying still higher octane quality motor fuels at as low cost as is possible.

In the case of aviation fuels, the same general type of problem confronts the refiner. Present-day aviation fuel specifications permit no more than 4.6 cc. of tetraethyllead per gallon and yet the refiner is being called upon to supply ultra high octane quality aviation fuels to permit increased power during take-off and climb, as well as increased cruise power and economy. Thus, once again the refiner is in the dilemma of having to supply at reasonable cost the extremely high octane quality gaso 3,272,600- Patented Sept. 13, 1966 "ice lines which are demanded by the more modern aviation engines.

It is seen that the need exists for a new Way of still further increasing fuel octane quality in an economical manner.

An object of this invention is to fulfill the foregoing need. Another object is to provide extremely high octane quality gasolines containing a high-1y effective addi tive complement. A further object is to provide antiknock fluid compositions made up of highly effective additive combinations which, when blended with high octane quality gasoline base stocks, cause substantial increases in antiknock performance. A particular object of this invention is to provide novel gasoline and antiknock fiuid compositions containing, inter alia, an extremely small concentration of a gasoline soluble compound of molybdenum which cooperates with the remainder of our novel additive complement and with the base fuel to provide especially high octane qualities. Other important objects of this invention will be apparent from the ensuing description.

The above and other objects of this invention are accomplished by providing gasoline having a motor octane number when clear (unleaded) of at least about 76 containing an organolead antiknock agent, preferably a tetraalkyllead compound containing from 1 to about 8 carbon atoms in each alkyl group, and a covalent molybdenum po'lycarbonyl compound, there being present in the gasoline'an amount of said agent equivalent to from about 1.58 to about 4.86 grams of elemental lead per gallon, and an' amount of said molybdenum compound equivalent to from about 0.003 to 0.150 gram of elemental molybdenum per gallon. These extremely small concentrations of the non-ionic molybdenum polycarbonyl compounds-insuflicient in themselves to materially raise the octane number of the unleaded base gasolinebring about tremendous improvements in the antiknock effectiveness of the lead alkyl antiknock agent contained in the fuels and antiknock fluids of this invention. In other words, the specified amount of lead alkyl is caused by these minute concentrations of molybdenum in the form of a covalent molybdenum polycarbonyl compound to exert the antiknock effectiveness that would ordinarily be exerted only by a much larger amount of lead alkyl in the absence of molybdenum. In short, these concentrations of molybdenum render a given quantity of lead alkyl much more eifective as an antiknock than it otherwise would be. Hence, in the compositions of this invention, the molybdenum ingredient acts as a promoter of the antiknock effectiveness of the lead alkyl.

Another embodiment of this invention is an antiknock fluid composition consisting essentially of an organolead antiknock agent, preferably a tetraalkyllead compound containing from 1 to about 8 carbon atoms in each alkyl group, and a covalent molybdenum polycarbonyl compound present in amount such that for every part by weight of elemental lead there is from about 0.0006 to 0.095 part by weight of elemental molybdenum. Such antiknock fluid compositions cause spectacular increases in antiknock quality when blended with high octane gasolinei.e., motor fuel and aviation fuel-in the proportions described above.

A preferred form of this invention is motor gasoline i.e., motor fuel-having a motor octane number when clear of at least about 76 containing an alkyllead antiknock agent, from about 0.4 to about 1.8 theories based on the lead of a halogen-containing scavenger, and a covalent molybdenum polycarbonyl compound, there being present in the gasoline an amount of said agent equivalent to from about 1.58 to about 3.17 grams of elemental lead per gallon, and an amount of molybdenum compound equivalent "to from about 0.003 to 0:150 gram of elemental molybdenum per gallon. Preferred scavenger complements for this form of the invention are made up of either 0.8 to about 1.2 theories based on the lead of a bromohydrocarbon scavenger or from about 0.4 to about 0.6 theory based on the lead of a bromohydrocarbon scavenger in conjunction with from about 0.8 to about 1.2 theories based on the lead of a chlorohydrocarbon scavenger. These particular scavenger complement-s very beneficially cooperate with the remainder of the ingredients of these motor fuel embodiments of the invention to produce outstanding promoter effects and at the same time efiectively control the amount and character of the engine deposits which are formed.

Another preferred form of this invention relates to aviation gasoline-i.e., aviation fuel-having a motor octane number when clear of at least about 80 containing an alkyllead antiknock agent, from about 0.8 to about 1.2 theories based on the lead of a halogen-containing scavenger, most preferably a bromohydrocarbon scavenger, and a covalent molybdenum polycarbonyl compound, there being present in the gasoline an amount of said agent equivalent to from about 1.58 to 4.86 grams of elemental lead per gallon, and an amount of said molybdenum compound equivalent to from about 0.003 to 0.150 gram of elemental molybdenum per gallon. Here again these relative proportions of the scavenger effectively cooperate with the remainder of the constituents of the aviation fuel to produce both a tremendous promoter effect and a very effective control of the amount and character of the engine deposits formed in the aviation engine.

Antiknock fluid compositions corresponding to the above preferred motor and aviation fuel mixtures form another part of this invention.

As an example of the astonishing behavior of the compositions of this invention, a liquid fuel composed of gasoline hydrocarbons having a motor octane number according to ASTM Test Procedure D-357 when clear of 80 containing 3 milliliters of tetraethyllead per gallon (3.17 grams of lead per gallon), and only 0.015 gram of molybdenum per gallon as molybdenum hexacarbonyl had a performance number of 100.9 (a motor octane number of 100.3). The concentration of the molybdenum compound in this fuel was so low that for every part of lead present there was only about five one-thousandths of a part of molybdenum. The corresponding fuel in the absence of the molybdenum compound had a performance number of 96.9 (a motor octane number 99.1). Thus, this infinitesimal amount of molybdenum in a fuel of this invention promoted the antiknock effectiveness of the tetraethyllead to such an extent that an improvement of four performance numbers (more than one motor octane number) was realized. To achieve this same gain in this fuel by the use of tetraethyllead in the absence of the trace amount of molybdenum, it is necessary to use 4.6 milliliters of tetraethyllead per gallon. Therefore, this extremely small concentration of molybdenum carbonyl in a fuel of this invention made 3.0 milliliters per gallon of tetraethyllead act as if 4.6 milliliters were present. Moreover, this enormous improvement in octane quality was achieved in a leaded gasoline composition which, in the absence of this trace concentration of the molybdenum compound, already had a particularly high octane quality a performance number of 96.9 (an octane number of 99.1). The attainment of such an improvement in this high octane region by refinery methods is extremely difficult and costly. It will also be seen that the attainment of this octane improvement could not have been accomplished in commercial motor fuel practice by the sole use of additional tetraethyllead since the maximum tetraethyllead concentration currently considered permissible would have to have been exceeded by a substantial margin.

Even more spectacular is the fact that a mere 0.07 gram per gallon of molybdenum as molybdenum hexacarbonyl in another fuel of this invention made 3.0 milliliters per gallon of tetraethyllead as powerful an antiknock as if 5.1 milliliters had been present. In other words, a gain of over five performance numbers was realized because of the promoter effect by the molybdenum compound.

It will be seen from the above examples that infinitesimally small concentrations of covalent molybdenum polycarbonyls bring about these exceedingly large promoter effects.

Examples of covalent molybdenum polycarbonyls which bring about the very variable results of this invention are molybdenum hexacarbonyl; aromatic molybdenum tricarbonyls, such as benzene molybdenum tricarbonyl, toluene molybdenum tricarbonyl, mesitylene molybdenum tricarbonyl, anisole molybdenum tricarbonyl, o-toluidine molybdenum tricarbonyl, N-methylaniline molybdenum tricarbonyl, biphenyl molybdenum tricarbonyl, etc.; cyclic amine molybdenum tricarbonyls, such as tripyridine molybdenum tricarbonyl, etc.; and cyclopentadienyl molybdenum carbonyls, such as cyclopentadienyl molybdenum tricarbonyl ethyl, methylcyclopentadienyl molybdenum tricarbonyl phenyl, dicyclopentadienyl dimolybdenum hexacarbonyl, etc. Thus, in general these poly.- carbonyls are characterized by containing 3 to 6 carbonyl groups in the molecule, by having a total of from 6 to about 24 carbon atoms in the molecule, and by having a plurality of covalent carbon-to-molybdenum bonds. On a cost-effectiveness basis, molybdenum hexacarbonyl is preferred. Also preferred are the cyclopentadienyl molybdenum carbonyls because of their favorable solubility, stability, and volatility characteristics. These tailor made compounds possess these beneficial characteristics of stability, volatility, and solubility because the different groups are bonded to the molybdenum in such a way that is given the electron configuration of the next higher inert gas, xenon, atomic number 54.

To formulate the antiknock fluid compositions of this invention, the constituents are blended together in appropriate quantity in a suitable container, such as a blending tank. The order of addition of the ingredients is not critical. Thus, they can be blended or mixed in any order or in various subcombinations. The fuels of this invention are prepared by blending the constituents of our additive complement in appropriate quantity with gasoline having a motor octane number clear of at least about 76. While the ingredients of our fuels can be blended separately in any order or in various subcombinations, a preferred formulation method involves blending an antiknock fluid composition of this invention in a suitable concentration with the appropriate base fuel. This method has the advantage of insuring the proper ratio of molybdenum and lead in the finished fuel especially since the molybdenum concentrations in the finished fuels are so small.

The following are example of compositions of this invention. The octane numbers of the fuels are motor octane numbers clear. By definition, a theory of bromine or chlorine equals two atoms of halogen per atom of lead.

EXAMPLE 1 octane gasoline blend containing per gallon: 3.17 grams of lead as tetraethyllead 0.03 gram of molybdenum as molybdenum hexacarbonyl EXAMPLE 2 80 octane gasoline blend containing per gallon: 3.17 grams of lead as tetraethyllead 0.15 gram of molybdenum as molybdenum hexacarbonyl EXAMPLE 3 80 octane gasoline blend containing per gallon:

3.17 grams of lead as tetraethyllead 0.5 theory of bromine as ethylene dibromide 1.0 theory of chlorine as ethylene dichloride 0.003 gram of molybdenum as molybdenum hexacarbonyl EXAMPLE 4 Premium motor gasoline (81.5 octane) containing per gallon:

1.58 grams of lead as tetraethyllead 0.5 theory of bromine as ethylene dibromide 0.9 theory of chlorine as 1,4-dich1orobutane 0.1 gram of molybdenum as xylene molybdenum tricarbonyl EXAMPLE 5 76 octane gasoline containing per gallon:

2.12 grams of lead as mixed methylethyllead compounds 0.6 theory of bromine as ethylene dibromide 1.0 theory of chlorine as ethylene dichloride 0.005 gram of molybdenum as isopropyl cyclopentadienyl molybdenum tricarbonyl methyl EXAMPLE 6 86 octane paraffinic gasoline containing per gallon:

4.86 grams of lead as tetrabutyllead 1.0 theory of bromine as propylene dibromide 0.07 gram of molybdenum as di-(methylcyclopentadienyl) dimolybdenum hexacarbonyl EXAMPLE 7 79.7 octane gasoline blend containing per gallon:

3.17 grams of lead as tetraethyllead 0.4 theory of bromine as ethylene dibromide 0.01 gram of molybdenum as tri-(4-ethylpyridine) molybdenum tricarbonyl EXAMPLE 8 92 octane gasoline blend containing per gallon:

3.17 grams of lead as tetraethyllead 0.25 theory of bromine as ethylene dibromide 0.50 theory of chlorine as ethylene dichloride 0.008 gram of molybdenum as methylcyclopentadienyl molybdenum tricarbonyl hexyl EXAMPLE 9 84 octane gasoline blend containing per gallon:

3.5 grams of lead as tetraethyllead 1.0 theory of bromine as ethylene dibromide 0.5 theory of chlorine as ethylene dichloride 0.13 gram of molybdenum as aniline molybdenum.

tricarbonyl EXAMPLE 10 88 octane gasoline blend containing .per gallon:

3.17 grams of lead as tetraethyllead 0.5 theory of bromine as ethylene dibromide 1.0 theory of chlorine as ethylene dichloride 0.08 gram of molybdenum as methylcyclopentadienyl methyl molybdenum tricarbonyl tricarbonyl EXAMPLE 13 Isooctane (100 octane) containing per gallon:

1.58 grams of lead as tetramethyllead 0.4 theory of bromine as dibromotoluene (mixed isomers) 0.8 theory of chlorine as 1,2,4-trichlorobenzene 0.02 gram of molybdenum as molybdenum hexacarbonyl 6 EXAMPLE 14 96.0 octane gasoline containing per gallon:

2.0 grams of lead as tetraa'myllead 0.6 theory of bromine as acetylene tetrabromide 1.2 theory of chlorine as hexlachlorobultadienc 0.12 gram of molybdenum as diethylcyclopentadienyl molybdenum tricarbonyl isopropyl EXAMPLE 15 81 octane gasoline blend containing per gallon:

2.5 grams of lead as tetraethyllead 0.5 theory of bromine as tert-butyl bromide 1.0 theory of chlorine as ethylene dichloride 0.14 gram of molybdenum a-s |tr-i-(4=metlroxypyridine) molybdenum tricarbonyl EXAMPLE 16 83 octane gasoline blend containing per gallon:

3.17 grams of lead as tetraethyllead 1.8 theory of chlorine as ethylene dichloride 0.004 gram of molybdenum as anisole molybdenum tricarbonyl EXAMPLE 17 79.7 octane gasoline blend containing per gallon:

3.17 grams of lead as tetraethyllead 0.5 theory of bromine as ethylene dibromide 1.0 theory of chlorine as ethylene dichloride 0.1 gram of molybdenum as methylcyclopentadienyl methyl molybdenum tricarbonyl EXAMPLE 18 83 octane gasoline containing per gallon:

4.0 grams of lead as met-hyltriethyllead 1.8 theory of bromide as ethyl-a-bromoacetate 0.09 gram of molybdenum as tripyridine molybdenum tricarbonyl EXAMPLE 19 88 octane number gasoline containing per gallon:

1.8 grams of lead as tetrapropyllead 0.8 theory of chlorine as 1,1-dicl1loro-2-nitroethane 0.006 gram of molybdenum as molybdenum hexacarbonyl EXAMPLE 20 92 octane number gasoline containing per gallon:

3.0 grams of lead as tetraethyllead 0.45 theory of bromine as 2,3-dibromobutane 1.0 theory of chlorine as ethylene dichloride 0.11 gram of molybdenum as m-toluidine molybdenum tricarbonyl EXAMPLE 21 98 octane number gasoline containing per gallon:

4.5 grams of lead as tetrahexyllead 1.6 theory of chlorine as carbon tetrachloride 0.009 gram of molybdenum as indenyl molybdenum tricarbonyl methyl EXAMPLE 22 77 octane number gasoline containing per gallon:

2.6 grams of lead as tetraethyllead 1.0 theory of bromine as ethylene dibromide 0.006 gram of molybdenum as 1,3,5-triethylbenzene molybdenum tricarbonyl EXAMPLE 23 octane number gasoline containing per gallon:

3.5 grams of lead as tetraphenyllead 0.4 theory of bromine as tert-butyl bromide 1.2 theory of chlorine as propylene dichloride 0.025 gram of molybdenum as benzene molybdenum tricarbonyl 1! EXAMPLE 24 100 octane number gasoline containing per gallon:

4.86 grams of lead as tetraethyllead 0.6 theory of bromine as mixed bromoxylenes 0.8 theory of chlorine as 1,4-dichlorobutane 0.075 gram of molybdenum as dicyclopentadienyl dimolybdenum hexacarbonyl EXAMPLE 25 Antiknock fluid consisting essentially of Methyltriethyllead 0.2 theory of bromine as 1-bromo-3-hydroxypropane 0.2 theory of chlorine as fi,,B-dichlorodiethyl ether 0.06 part by weight of molybdenum as molybdenum hexacarbonyl per 100 parts of lead EXAMPLE 26 Antiknock fluid consisting essentially of:

Tetraethyllead 9.5 parts by weight of molybdenum as mesitylcne molybdenum tricarbonyl per 100 parts of lead EXAMPLE 27 Antiknock fluid consisting essentially of:

Tetraisopropyllead 0.7 theory of bromine as 1,2,3-tribromopropane 0.7 theory of chlorine as 1,1-dichloro-2-nitroethane 0.5 part by weight of molybdenum as ethylcyclopentadienyl molybdenum tricarbonyl hydride per 100 parts of lead EXAMPLE 28 Antiknock fluid consisting essentially of:

Tetrahexyllead 1.4 theory of chlorine as 1,2,4-trichlorobenzene 1.0 part by weight of molybdenum as cyclopentadienyl molybdenum tricarbonyl propyl per 100 parts of lead EXAMPLE 29 Antiknock fluid consisting essentially of:

Tetraoctyllead 1.6 theory of bromine as propylene dibromide 0.2 theory of chlorine as 1,5-dichloropentane 5.0 parts by weight of molybdenum as tripicoline molybdenum tricarbonyl per 100 parts of lead EXAMPLE 30 Antiknock fluid consisting essentially of:

Dimethyldibutyllead 0.9 theory of bromine as 2-methyl-2-bromobutane 0.2 part by weight of molybdenum as trilutidine molybdenum tricarbonyl per 100 parts of lead EXAMPLE 31 The antiknock fluid compositions of Examples 25-30 inclusive are blended in the following respective concentrations with a gasoline having an octane number of 82: 1.58; 2.0; 2.8; 3.5; 4.0; and 4.86 grams of lead per gallon.

EXAMPLE 32 Tetraethyllead and methylcyclopentadienyl phenyl molybdenum tricarbonyl are admixed so that the ratio is eight grams of lead as tetraethyllead present for every 0.1 gram of molybdenum present as methylcyclopentadienyl phenyl molybdenum tricarbonyl. In this composition there is 0.0125 part of molybdenum per part of lead.

EXAMPLE 33 To the composition of Example 33 is added ethylene dibromide in amount so that there is one theory of scavenger present based upon the amount of tetraethyllead.

Excellent antiknock qualities are exhibited by the fuels of this invention, such as those shown in the above illustrative examples. To illustrate, the fuels of l and 2 were compared with an identical leaded fuel not containing the molybdenum compound using the Motor Method (ASTM D-357). The results of these tests are shown in Table I.

TABLE I.Effect of fuel additives on fuel antiknock 1 Performance number.

2 Octane number.

3 Total amount of TEL (00.) required in the fuel in the absence of molybdenum to provide the same octane quality.

In every case the fuels of this invention had much higher octane qualities due to the presence therein of the extremely small amount of the molybdenum compound. This shows the tremendous magnitude of the promoter effect characteristic of this invention.

Similarly, the fuel of Example 11 was compared with identical fuel not containing the molybdenum compound using the Research Method (ASTM D-908). The data are in Table II.

TABLE II.Efiect of fuel additives on fuel antiknock quality Octane Quality Im- Octane Quality provemcnt Due to Pro- Example G. Mo/gal. meter PN ON IN ON Ce. TEL

None 90.0 06.9 11 0.007 92. 4 97. 7 2. 4 0.8 3. 7

Shown once again by the above data is the fact that an infinitesimally small amount of molybdenum (there was only two one-thousandths of a part of molybdenum per part of lead) in a fuel of this invention brought about an astonishingly great promoter effect. However, when the identical leaded fuel contains 0.180 gram of molybdenum per gallon as molybdenum hexacarbonyl and is subjected to the same antiknock test procedure, it is found that a very substantial antagonistic effect occurs. Thus, instead of getting the above-described valuable promoter effect, this larger amount of molybdenum as molybdenum hexacarbonyl causes a marked depreciation in the octane value of the fuel. Specifically, the research octane number of this leaded fuel containing 0.180 gram of molybdenum per gallon is reduced from 96.9 (no molybdenum present) to 95.2. In terms of performance numbers, the presence of this amount of molybdenum as molybdenum hexacarbonyl results in a drop from 90.0 to 85.4. In other words, even though this fuel contains 3.0 milliliters of tetraethyllead per gallon, this higher amount of molybdenum is so mutually antagonistic therewith that the resultant octane number is equivalent to that produced by only 2.1 milliliters of tetraethyllead by gallon in the same fuel in the absence of molybdenum. This shows that molybdenum hexacarbonyl is not a promoter-and is in fact an antiknock antagonistwhen it is used at concentrations exceeding those called for by this invention.

In still another engine test, a fuel of this invention made from a gasoline blend having a motor octane number clear of and containing 3.0 milliliters of tetraethyllead and only 0.03 gram of molybdenum per gallon gave a performance number by the motor method of 121.9. The same leaded fuel in the absence of molybdenum had a performance number by the same method of 120.4. It is seen that the molybdenum cooperated with the lead to provide an increase of 1.5 performance numbers. Such a great improvement in octane quality is especially significant because it occurred in a gasoline base stock which already had a very high octane quality.

Lead alkyls which can be used in the compositions of this invention included tetramethyllead, tetraethyllead, tetrapropyllead, tetraisopropyllead, tetrabutyllead, methyltriethyllead, dimethyldiethyllead, trimethylethyllead, tetraoctyllead, and the like, or mixtures thereof. Thus, each alkyl group can contain from 1 to about 8 carbon atoms and be straight or branched chain. Other organolead compounds, such as tetratolyllead, dimethyldiphenyllead, etc., can be used. The use of tetraethyllead is preferred because of its superior performance qualities, commercial availability, and lower cost.

The bromine-containing and chlorine-containing scavengers which can be used in the fuels and fluids of this invention are organic halide compounds with react with the lead during combustion in the engine to form volatile lead halides. I-Ialohydrocarbon scavengersespecia1ly those having a vapor pressure of 0.1 to 250 millimeters of mercury at 50 F.-are preferred because of their generally superior storage stability although other scavengers can be employed successfully. Useful scavengers include ethylene dichloride; ethylene dibromide; carbon tetrachloride; propylene dibromide; 2-chloro-2,3-dibromobutane; 1,2,3 tribromopropane; hexachloropropylene; mixed bromoxylenes; 1,4-dibrombutane; 1,4-dichloropentane; {3,13'-d-ibromodiisopropyl ether; trichlorobenzene; dibromotoluenes; tert-butyl bromide; Z-methyl-Z-bromobutane; 2,3,3-trimethyl-2-bromobutane; tert-butyl chloride; 2,3-dimet hyl-2,3-dibromobutane; 2,5-dirnethyl-2,5 dibromohexane; 2-methyl-2,3-dibromobutane; 2-methyl-2,3di' bromobutane; 2-metl1yl-2,3-dichloroheptane; 2-methyl-2,4- dibromohexane; 2,4-dibromopentane; 2,5-dichlorohexane; 3-methyl-2,4-dibromopentane; l-phenyl 1 chloroethane; ethyl-a-bromoacetate; diethyldibromomalonate; propyl-achlorobutyrate; 1,l-dichloro-l-nitroethane; 1,1-dichloro-2 nitroethane; 1,l-dibromo-l-nitrobutane; 2-chloro-4-nitropentane; 2,4-dibromo-3-nitropentane; 1-chl0ro-2-hydroxyethane; 1r-bromo-3-hydroxypropane; l-bromo-3-hydroxybutane; 3-methyl-2-bromo-4-hydroxypentane; 3,4-dimethyl-2-bromo-4-hydroxypentane; and, in general, scavengers (and lead alkyl antiknock agents) disclosed in U.S. Patents 1,592,954; 1,668,022; 2,3 64,921; 2,398,281; 2,479,- 900; 2,479,901; 2,479,902; 2,479,903; 2,496,983; 2,661,- 379; and 2,822,252.

Particularly prepared scavenger mixtures for the motor fuels of this invention are 0.5 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride; 0.6 theory of bromine as ethylene dibromide and 1.0 theory of chlorine as ethylene dichloride; and 0.45 theory of bromine as 2,3-dibromobutane and 1.0 theory of chlorine as ethylene dichloride. These mixtures effectively control the amount of deposits formed in the engine during operation and bring about this desirable result at a minimum cost.

The methods for making the above lead alkyls and scavengers are well known to those skilled in the art and can be found in the literature. Methods of preparing the molybdenum compounds described herein have also been reported. See, for instance, U.S. 2,554,194; U.S. 2,818,- 416; Z. anorg. allgem Chem. 221, 337-48 (1935); and Naturwissenschaften 42, 625 (1955).

Other ingredients which can be used with advantage in the fuels of this invention include dyes for identification purposes; metal deactivators, such as N,N'-di-salicylidene- 1,2-diamino-propane; anti-icing and anti-rust additives; surface ignition control additives, such as tricresylphosphate, tri(,B -chloropropyl) thionophosphate, dimethyl- 10 phenylphosphate, dimethyltolylphosphate, dimethylxylylphosphate, trimethylphosphate, 'dixylylphosphoramidate, trialkylphosphines, etc., antioxidants; and the like.

The gasoline base stocks employed in this invention are preferably those which boil within or throughout the gasoline boiling range. For motor fuels, this range is from about to about 420 F. For best results the motor fuel should have a percent boiling point of at least about 310 F. and an endpoint of at least about 375 F. Aviation fuels generally boil in the range of about 80 to about 340 F. These fuel base stocks are derived from a variety of refinery processes and include straight run gasoline, catalytically or thermally cracked stocks, or gasoline hydrocarbons resulting from such processes as reforming, polymerization, isomerization, and the like. Individual gasoline hydrocarbons or various blends thereof can be used successfully. As stated above, the chief requisite of the gasoline base stock is that it have a motor octane number clear of at least 76.

We claim:

1. A spark ignition internal combustion engine fuel composition consisting essentially of petroleum hydrocarbons boiling Within the gasoline boiling range and having a motor octane number when clear of at least about 76, containing an antiknock amount of an organolead antiknock agent selected from the class consisting of alkyllead antiknock agents and aryllead antiknock agents, said antiknock amount being equivalent to from about 0.158 to about 4.86 grams of elemental lead per gallon, having a small amount, sulficient to provide a synergistic octane quality improvement in combination with said organolead compound, but insuflicient in itself to materially raise the octane number of the unleaded base gasoline, of a mononuclear aromatic molybdenum tricarbonyl wherein the aromatic portion is an aromatic hydrocarbon molecule, said small amount being equivalent to from about 0.003 to 0.150 gram of elemental molybdenum per gallon.

2. The composition of claim 1 wherein said antiknock amount is equivalent to from about 1.58 to about 3.17 grams of elemental lead per gallon and wherein said composition additionally contains from about 0.4 to about 1.8 theories based on the lead of a halogen containing scavenger.

3. A spark ignition internal combustion fuel composition consisting essentially of petroleum hydrocarbons boiling within the gasoline boiling range and having a motor octane number when clear of at least about 76, containing an antiknock amount of a tetraalkyllead antiknock compound and a small amount, sufficient to provide a synergistic octane quality improvement in combination with said tetraalkyllead compound, of a mononuclear aromatic molybdenum tricarbonyl wherein the aromatic portion is an aromatic hydrocarbon molecule.

References Cited by the Examiner UNITED STATES PATENTS 1,579,803 4/1926 Babb 4469 1,779,061 10/1930 Danner et al. 4468 1,954,865 4/1934 Danner 44-67 2,086,775 7/ 1937 Lyons et al. 4468 2,375,236 5/1945 Miller 44-68 2,410,829 11/1946 Luten 4467 2,445,778 7/ 1948 Hale 44-68 2,818,416 12/1957 Brown et al. 44-68 2,881,062 4/1959 Bishop 4468 2,902,983 9/ 1959 Patberg 44-67 FOREIGN PATENTS 1,095,084 12/ 1954 France.

DANIEL E. WYMAN, Primary Examiner.

JULIUS GREENWALD, JOSEPH R. LIBERMAN, I E.

DEMPSEY, Assistant Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,272,606 September 13, 1966 Jerome E Brown et al.

5 in the above numbered patthat error appear Patent should read as It is hereby certified d that the said Letters ent requiring correction an corrected below.

read valuable line 11, for "variable Column 4,

for 0.006 read column 6, line 66,

Signed and sealed this 24th day of October 1967.,

(SEAL) Attest:

Edward M. Fletcher, I r. EDWARD J. BRENNER Commissioner of Patents Attesting Officer 

1. A SPARK IGNITION COMBUSTION ENGINE FUEL COMPOSITION CONSISTING ESSENTIALLY OF PETROLEUM HYDROCARBONS BOILING WITHIN THE GASOLINE BOILING RANGE AND HAVING A MOTOR OCTANE NUMBER WHEN CLEAR OF AT LEAST ABOUT 76, CONTAINING AN ANTIKNOCK AMOUNT OF AN ORGANOLEAD ANTIKNOCK AGENT SELECTED FROM THE CLASS CONSISTING OF ALKYLLEAD ANTIKNOCK AGENTS AND ARYLLEAD ANTIKNOCK AGENTS, SAID ANTIKNOCK AMOUNT BEING EQUIVALENT TO FROM ABOUT 0.158 TO ABOUT 4.86 GRAMS OF ELEMENTAL LEAD PER GALLON, HAVING A SMALL AMOUNT, SUFFICIENT TO PROVIDE A SYNERGISTIC OCTANE QUANTITY IMPROVEMENT IN COMBINATION WITH SAID ORGANOLEAD COMPOUND, BUT INSUFFICIENT IN ITSELF TO MATERIALLY RAISE THE OCTANE NUMBER OF THE UNLEADED BASE GASOLINE, OF A MONONUCLEAR AROMATIC MOLYBDENUM TRICARBONYL WHEREIN THE AROMATIC PORTION IS AN AROMATIC HYDROCARBON MOLECULE, SAID SMALL AMOUNT BEING EQUIVALENT TO FROM ABOUT 0.003 TO 0.150 GRAM OF ELEMENTAL MOLYBDENUM PER GALLON. 